SpatialPixelsTopography: Creates a 'SpatialPixelsTopography'

Description

Function SpatialPixelsTopography creates an object of class SpatialPixelsTopography-class containing topographic variables for a set of points.

Usage

SpatialPixelsTopography(
  points,
  elevation,
  slope,
  aspect,
  tolerance = sqrt(.Machine$double.eps),
  proj4string = CRS(as.character(NA)),
  round = NULL,
  grid = NULL
)

Value

Function SpatialPixelsTopography returns an object 'SpatialPixelsTopography-class'.

Arguments

points: An object of class SpatialPoints-class or a numeric matrix of coordinates.
elevation: Elevation values (in m) of the points.
slope: Slope values (in degrees) of the points.
aspect: Aspect values (in degrees from North) of the points.
tolerance: Precision up to which extent points should be exactly on a grid.
proj4string: Object of class CRS in the first form only used when points does not inherit from Spatial.
round: default NULL, otherwise a value passed to as the digits argument to round for setting cell size.
grid: Grid topology using an object of class GridTopology; a value of NULL implies that this will be derived from the point coordinates.

Author

Miquel De Cáceres Ainsa, CREAF

Examples

Run this code


data(examplegridtopography)

#Creates spatial topography pixels as a subset of points in the grid
spt = as(examplegridtopography,"SpatialPointsTopography")
cc = spt@coords
center = 5160
d = sqrt((cc[,1]-cc[center,1])^2+(cc[,2]-cc[center,2])^2)
p = which(d<3000) #Select points at maximum distance of 3km from center
spxt = SpatialPixelsTopography(spt[p], spt$elevation[p],
                              spt$slope[p],
                              spt$aspect[p])

#Alternatively, use coercing and subsetting (drop = TRUE causes grid to be recalculated) 
spxt = as(examplegridtopography, "SpatialPixelsTopography")[p, drop=TRUE]          
                              
#Display data
spplot(spxt, variable="elevation", scales=list(draw=TRUE))
spplot(spxt, variable="slope", scales=list(draw=TRUE))
spplot(spxt, variable="aspect", scales=list(draw=TRUE))